After seeing the stairs in the Small Walls 1.5 mod, I thought how cool would it be if Rimworld had a second floor view. I know that multiple levels (like in Dwarf Fortress) will probably never be implemented, but I thought maybe it would be enough to have a switch in game that would simply show the roofs of all buildings and maybe enable the player to build things like defenses on top of the roofs. Then make the Colonists disappear from the players view when they walk on a roof while in "first level view" and reappear when they leave the roof.

Some may now say: "Why stop at one level, why not have several stories and layers and make it a huge, complex mess that no one will enjoy! It's a bad idea to implement just one additional layer to the game and it's too much to add several!"
I agree but I think it would be cool to be able to make things like walkable walls, watchtowers and sun roofs. I think just a simple mode (not a whole new world layer) where roofs would be visible would be enough for this.

So what do you guys think? Has this been proposed before? Would it be impossible to make? Could it maybe be made with a mod?

Some may now say: "Why stop at one level, why not have several stories and layers and make it a huge, complex mess that no one will enjoy! It's a bad idea to implement just one additional layer to the game and it's too much to add several!"
I agree but I think it would be cool to be able to make things like walkable walls, watchtowers and sun roofs. I think just a simple mode (not a whole new world layer) where roofs would be visible would be enough for this.

So what do you guys think? Has this been proposed before? Would it be impossible to make? Could it maybe be made with a mod?